Capacitors are used in semiconductor devices for a variety of purposes in a variety of functional circuits, such as mixed signal circuits, analog circuits, radio frequency (RF) circuits, dynamic random access memory (DRAM), embedded DRAM (eDRAM), and logic operation circuits. One purpose for which a capacitor is used is as a decoupling capacitor, wherein the decoupling capacitor is placed between power contacts to eliminate or reduce noise on the power lines, thereby preventing power spikes on the power lines from damaging other circuitry.
In an attempt to incorporate the decoupling capacitor with the other circuitry, the decoupling capacitor has been placed on-chip. One attempt at using an on-chip decoupling capacitor utilizes a thin-film planar capacitor. These capacitors, however, generally require large areas and are difficult to design and fabricate such that the capacitors have a sufficiently large enough capacitance.
In an attempt to increase the capacitance of the decoupling capacitor, metal-insulator-metal (MIM) capacitors have been used. MIM capacitors comprise metallic layers with a dielectric layer interposed therebetween formed in a trench of a dielectric layer. Placing the MIM coupling capacitors on-chip, however, is limited by the amount of area and the routing lines. For example, the MIM decoupling capacitors may require a significant amount of space and care must be taken regarding the placement. As a result, the resulting chip size is increased.
Accordingly, what is needed in the art are schemes for integrating decoupling MIM capacitors on a chip that requires less overall chip area.